This invention relates to a a weighing system for weighing each load handled by a load handling apparatus and for accumulating the total weight of the material transferred; and to a method for weighing bulk material during such handling by a load handling apparatus.
This invention is concerned with the use of loading machines, commonly referred to as front end loaders, for the loading of bulk material such as gravel from ground stock piles onto transport vehicles such as railroad cars or trucks. It is important that these vehicles be loaded to maximum legal capacity for a number of reasons. In the case of railroad cars, when the cars are underloaded, such underloading simply represents loss of gross sales when railroad cars are in short supply because the shipper is simply not utilizing the shipping capacity which is available. If a car is overloaded, and this is not discovered until the car is weighed in the railroad yard, the cost of reducing the load is very expensive in terms of man hours and equipment; and, in addition, the material unloaded is either lost or can only be marketed at greatly reduced value.
In the case of transport trucks, the penalty for underloading is the same as that for railroad cars; and the penalty for overloading includes fines and possible loss of material which must be unloaded. It is important then that means be provided for loading vehicles accurately so that they can be loaded near legal capacity with minimum risk of overloading.
While experienced loader operators may be able to estimate very closely the loads which are being loaded onto a transport truck or railroad car, this is only possible where the loader operator is able to visually observe the load in the bucket, and has the experience to estimate the weight of the particular material which is being loaded. It is a fact, however, that for many large capacity loaders, the load in the bucket is not visible to the operator; and it is necessary therefore to provide some form of automatic system for weighing each bucket load and, preferably, to accumulate the weights of the several bucket loads which are loaded onto the transport vehicle.
A principal object of this invention is to provide a weighing system and method for use with hydraulic loading apparatus, to enable the loading of a transport vehicle to maximum capacity without overload.
Another object of this invention is to provide a system and method for the precision weighing of bulk materials loaded from a stockpile onto a transport vehicle, while the material is being loaded.
A further object of this invention is to provide a system and method for the precision weighing of each bucket load transferred to another location.
Still another object of this invention is to provide a hydraulic loader having a self-contained system for weighing each bucket load, and for accumulating the weight of a series of bucket loads which are transferred to another location.
A still further object of this invention is to provide a weighing system and method for a hydraulic loader, for weighing bulk material loaded onto a transport vehicle efficiently with minimum loss of operator time.
These objects are accomplished in a system for measuring and indicating the weight of a load. A transducer is operatively connected to a load supporting apparatus for producing an instantaneous electric analog signal proportional to the supported weight. A converter converts that analog signal to a frequency signal consisting of pulses generated at a frequency proportional to the analog signal. A gate is controlled by a clock which provides periodic gate open intervals of preselected uniform time and passes the frequency signal to a counter for counting and displaying the pulses which are representative of the supported load. An actuator coupled to the gate enables initiating single gate open intervals for each load, so that the counter may function as an accumulator counter. More particularly the system may include a second counter which continuously displays the weight of the instant supported load, the first mentioned counter and actuator means functioning to accumulate the weight for successive loads handled by the load supporting apparatus.
These objects are accomplished in a method which includes the steps: detecting a load by means of a transducer connected to a load supporting apparatus and producing an electric analog output signal; converting that analog signal to a frequency signal consisting of pulses generated at a frequency proportional to the analog signal; generating that frequency signal as a continuous signal; counting pulses of the frequency signal during a preselected time period, to represent a supported load; storing the counted pulses in an accumulator counter, to accumulate the weights of successive supported loads. More particularly the method includes the steps: passing the pulses of the frequency signal to an automatically resettable unit counter which continuously displays the weight of the instant load; and passing the pulses to the accumulator counter during only one time interval for each successive supported load.
The novel features and the advantages of the invention as well as additional objects thereof, will be understood more fully from the following description when read in connection read in connection with the accompanying drawings.